Haplogroup I2 (Y-DNA) is Continental Europe's Mesolithic paternal lineage. In human genetics, Haplogroup I-M438 is a Y-chromosomehaplogroup. Until 2008, it was known as Haplogroup I1b, but it is now named I2 (ISOGG 2013). Haplogroup I-M438 might have originated in Southeastern Europe some 15,000 - 17,000 years ago and developed into three main subgroups : I-M438*, I-L460, and I-L1251.

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Origin and prehistoric presence[edit]

Haplogroup I-P37.2 has been identified in neolithic human remains in Europe. Two samples (10%) of ancient Y-DNA from Treilles, the type-site of a Late Neolithic group of farmers on the east Pyrenees shore on France's southern border, dated to about 3000 BC tested positive for M438 and P37.2. The culture predates the Bell Beaker and Corded Ware Culture in Europe. The remains were found in association with 90% others testing positive for Haplogroup G2a (p15+).[3] A study of earlier Neolithic human remains at Derenburg Meerenstieg II in Germany linked to the Linear Band Culture dated to 5500-4900 BC found two remains that tested positive for Haplogroup F, but negative for haplogroup G,H,I,J or K (positive for M89 but negative for markers M201,M69, M170, M304, and M9). These remains were found in association with remains testing positive for G2a3 (SNP S126 or L30).[4]

Subclades[edit]

Note: The systematic subclade names have changed several times in recent years, and they are likely to change again, as new markers are discovered which clarify the sequential branching of the tree. The scheme below is taken from ISOGG,[5] which updates (Ytree 2013) Karafet et al. (2008).[6]

I-M26 (L158, L159.1/S169.1, M26) Typical of the population of the so-called "archaic zone" of Sardinia; also found at low frequencies among populations of Southwest Europe, particularly in Castile, Béarn, and the Basque Country

I-P37.2[edit]

The subclade divergence for I-P37.2 occurred 10.7±4.8 kya. The age of YSTR variation for the P37.2 subclade is 8.0±4.0 kya[2]

I-L158[edit]

Haplogroup I-L158 (L158, L159.1/S169.1, M26) accounts for approximately 40% of all patrilines among the Sardinians.[8] It is also found at low to moderate frequency among populations of the Pyrenees (9.5% in Bortzerriak, Navarra; 9.7% in Chazetania, Aragon; 8% in Val d'Aran, Catalunya; 2.9% in Alt Urgell, Catalunya; and 8.1% in Baixa Cerdanya, Catalunya) and Iberia, and it has been found in 1.6% of a sample of Albanians living in the Republic of Macedonia[9] and 1.2% (3/257) of a sample of Czechs.[10] The age of YSTR variation for the M26 subclade has been calculated at 8.0±4.0 kya.[2]

I-L178[edit]

I-L178 is very rare, but has been found in two persons from Germany and one from Poland. The age of YSTR variation for the M423 subclade is 8.8±3.6 kya.[11]

I-L69.2[edit]

I-L69.2 (L69.2(=T)/S163.2) {rs9786274} is typical of the South Slavic populations of south-eastern Europe, being highest in Bosnia-Herzegovina (>50%).[1] Haplogroup I-L69.2 is also commonly found in north-eastern Italians.[12] There is also a high concentration of I-L69.2 in north-east Romania, Moldova and western Ukraine. Several groups have determined the common occurrence of this subclade in the South Slavic-speaking populations to be the result of "pre-Slavic" paleolithic settlement in the region. Peričić et al. for instance places its expansion to have occurred "not earlier than the YD to Holocene transition and not later than the early Neolithic”.[13][14][15] Decidedly, the Slavic population can be divided into two genetically distinct groups: one encompassing all Western-Slavic (Poles, Slovaks etc.), Eastern-Slavic (Russians, Ukrainians etc.), and a few Southern-Slavic populations (north-western Croats and Slovenes), characterized by Haplogroup R1a, and one encompassing all remaining Southern Slavs, and Rumanians, characterized by Haplogroup I2a2 (I-L69.2). According to Rebała et al., this phenomenon is explained by "contribution to the Y chromosomes of peoples who settled in the Balkan region before the Slavic expansion to the genetic heritage of Southern Slavs.."[16]

Haplogroup I-M223 can be further subdivided in several subclades designated in the Y2012 ISOGG tree as follows: Haplogroup I-M223* with no further known polymorphisms, Haplogroup I-M284 defined by M284 polymorphism and including an undergroup Haplogroup I-L126 reserved for individuals derived for the L126/S165, L137/S166 polymorphisms, Haplogroup I-L701 associated with L701 polymorphism, and Haplogroup I-Z161 denoting individuals derived for the Z161 polymorphism.[citation needed]

I-M284[edit]

Haplogroup I2a2a1a1 (ISOGG 2014). I-M284 has been found almost exclusively among the population of Great Britain, suggesting that the clade may have arisen in that island. I-M284 is comparatively rare in Ireland except in the north-east. In regard to north-east Ireland, the presence of this subclade "provides some tentative evidence of ancient flow with eastern areas that could support the idea that the La Tene cultural package was accompanied by some migration."[19] Where it is found in those of Irish descent with Gaelic surnames, this suggests an ancestor who arrived in Ireland from Celtic Britain.[19] Men with several Gaelic surnames such as McGuinness and McCartan bear this subclade, family groups that have a historically recorded 6th-century common ancestor, thus it is not the result of known recent gene flow between Britain and Ireland.[19] While subclades of I-M284 are atypical of Ireland they are relatively common in continental Europe.[19] The observed mutational divergence between men with this subclade suggests its foundation very approximately at 300 BC, thus dates and geography are circumstantially associated but not securely with Iron Age continental Europe.[19]

I-Z161[edit]

Haplogroup I2a2a1b2 (ISOGG 2014). Z161+ defines the I2 Continental clade (except Continental 3). Its age is estimated around 7.000 years old. It is mainly found in North Europe, especially in Denmark, Germany, the Netherlands, and England. In Northwest Sicily it can also be found believed to be due to remnants of a Norman settlement.

^ abcdeMcEvoy and Bradley, Brian P and Daniel G (2010). Celtic from the West Chapter 5: Irish Genetics and Celts. Oxbow Books, Oxford, UK. pp. 117 They identify this haplogroup subclade as a mutation of I1c, using the old nomenclature. ISBN978-1-84217-410-4.